website/v1.1/reference/docker-cli-to-kubectl.md

title
kubectl for docker users

In this doc, we introduce the Kubernetes command line for interacting with the api to docker-cli users. The tool, kubectl, is designed to be familiar to docker-cli users but there are a few necessary differences. Each section of this doc highlights a docker subcommand explains the kubectl equivalent.

Table of Contents

docker run

How do I run an nginx container and expose it to the world? Checkout kubectl run.

With docker:

{% highlight console %} {% raw %} $ docker run -d --restart=always -e DOMAIN=cluster --name nginx-app -p 80:80 nginx a9ec34d9878748d2f33dc20cb25c714ff21da8d40558b45bfaec9955859075d0 $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a9ec34d98787 nginx "nginx -g 'daemon of 2 seconds ago Up 2 seconds 0.0.0.0:80->80/tcp, 443/tcp nginx-app {% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

start the pod running nginx

$ kubectl run --image=nginx nginx-app --port=80 --env="DOMAIN=cluster" replicationcontroller "nginx-app" created

expose a port through with a service

$ kubectl expose rc nginx-app --port=80 --name=nginx-http {% endraw %} {% endhighlight %}

With kubectl, we create a replication controller which will make sure that N pods are running nginx (where N is the number of replicas stated in the spec, which defaults to 1). We also create a service with a selector that matches the replication controller's selector. See the Quick start for more information.

By default images are run in the background, similar to docker run -d ..., if you want to run things in the foreground, use:

{% highlight console %} {% raw %} kubectl run [-i] [--tty] --attach --image= {% endraw %} {% endhighlight %}

Unlike docker run ..., if --attach is specified, we attach to stdin, stdout and stderr, there is no ability to control which streams are attached (docker -a ...).

Because we start a replication controller for your container, it will be restarted if you terminate the attached process (e.g. ctrl-c), this is different than docker run -it. To destroy the replication controller (and it's pods) you need to run kubectl delete rc <name>

docker ps

How do I list what is currently running? Checkout kubectl get.

With docker:

{% highlight console %} {% raw %} $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a9ec34d98787 nginx "nginx -g 'daemon of About an hour ago Up About an hour 0.0.0.0:80->80/tcp, 443/tcp nginx-app {% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %} $ kubectl get po NAME READY STATUS RESTARTS AGE nginx-app-5jyvm 1/1 Running 0 1h {% endraw %} {% endhighlight %}

docker attach

How do I attach to a process that is already running in a container? Checkout kubectl attach

With docker:

{% highlight console %} {% raw %} $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a9ec34d98787 nginx "nginx -g 'daemon of 8 minutes ago Up 8 minutes 0.0.0.0:80->80/tcp, 443/tcp nginx-app $ docker attach -it a9ec34d98787 ... {% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %} $ kubectl get pods NAME READY STATUS RESTARTS AGE nginx-app-5jyvm 1/1 Running 0 10m $ kubectl attach -it nginx-app-5jyvm ...

{% endraw %} {% endhighlight %}

docker exec

How do I execute a command in a container? Checkout kubectl exec.

With docker:

{% highlight console %} {% raw %}

$ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a9ec34d98787 nginx "nginx -g 'daemon of 8 minutes ago Up 8 minutes 0.0.0.0:80->80/tcp, 443/tcp nginx-app $ docker exec a9ec34d98787 cat /etc/hostname a9ec34d98787

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl get po NAME READY STATUS RESTARTS AGE nginx-app-5jyvm 1/1 Running 0 10m $ kubectl exec nginx-app-5jyvm -- cat /etc/hostname nginx-app-5jyvm

{% endraw %} {% endhighlight %}

What about interactive commands?

With docker:

{% highlight console %} {% raw %}

$ docker exec -ti a9ec34d98787 /bin/sh

exit

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl exec -ti nginx-app-5jyvm -- /bin/sh

exit

{% endraw %} {% endhighlight %}

For more information see Getting into containers.

docker logs

How do I follow stdout/stderr of a running process? Checkout kubectl logs.

With docker:

{% highlight console %} {% raw %}

$ docker logs -f a9e 192.168.9.1 - - [14/Jul/2015:01:04:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.35.0" "-" 192.168.9.1 - - [14/Jul/2015:01:04:03 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.35.0" "-"

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl logs -f nginx-app-zibvs 10.240.63.110 - - [14/Jul/2015:01:09:01 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-" 10.240.63.110 - - [14/Jul/2015:01:09:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"

{% endraw %} {% endhighlight %}

Now's a good time to mention slight difference between pods and containers; by default pods will not terminate if their processes exit. Instead it will restart the process. This is similar to the docker run option --restart=always with one major difference. In docker, the output for each invocation of the process is concatenated but for Kubernetes, each invocation is separate. To see the output from a previous run in Kubernetes, do this:

{% highlight console %} {% raw %}

$ kubectl logs --previous nginx-app-zibvs 10.240.63.110 - - [14/Jul/2015:01:09:01 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-" 10.240.63.110 - - [14/Jul/2015:01:09:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"

{% endraw %} {% endhighlight %}

See Logging for more information.

docker stop and docker rm

How do I stop and delete a running process? Checkout kubectl delete.

With docker

{% highlight console %} {% raw %}

$ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a9ec34d98787 nginx "nginx -g 'daemon of 22 hours ago Up 22 hours 0.0.0.0:80->80/tcp, 443/tcp nginx-app $ docker stop a9ec34d98787 a9ec34d98787 $ docker rm a9ec34d98787 a9ec34d98787

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl get rc nginx-app CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS nginx-app nginx-app nginx run=nginx-app 1 $ kubectl get po NAME READY STATUS RESTARTS AGE nginx-app-aualv 1/1 Running 0 16s $ kubectl delete rc nginx-app NAME READY STATUS RESTARTS AGE nginx-app-aualv 1/1 Running 0 16s $ kubectl get po NAME READY STATUS RESTARTS AGE

{% endraw %} {% endhighlight %}

Notice that we don't delete the pod directly. With kubectl we want to delete the replication controller that owns the pod. If we delete the pod directly, the replication controller will recreate the pod.

docker login

There is no direct analog of docker login in kubectl. If you are interested in using Kubernetes with a private registry, see Using a Private Registry.

docker version

How do I get the version of my client and server? Checkout kubectl version.

With docker:

{% highlight console %} {% raw %}

$ docker version Client version: 1.7.0 Client API version: 1.19 Go version (client): go1.4.2 Git commit (client): 0baf609 OS/Arch (client): linux/amd64 Server version: 1.7.0 Server API version: 1.19 Go version (server): go1.4.2 Git commit (server): 0baf609 OS/Arch (server): linux/amd64

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl version Client Version: version.Info{Major:"0", Minor:"20.1", GitVersion:"v0.20.1", GitCommit:"", GitTreeState:"not a git tree"} Server Version: version.Info{Major:"0", Minor:"21+", GitVersion:"v0.21.1-411-g32699e873ae1ca-dirty", GitCommit:"32699e873ae1caa01812e41de7eab28df4358ee4", GitTreeState:"dirty"}

{% endraw %} {% endhighlight %}

docker info

How do I get miscellaneous info about my environment and configuration? Checkout kubectl cluster-info.

With docker:

{% highlight console %} {% raw %}

$ docker info Containers: 40 Images: 168 Storage Driver: aufs Root Dir: /usr/local/google/docker/aufs Backing Filesystem: extfs Dirs: 248 Dirperm1 Supported: false Execution Driver: native-0.2 Logging Driver: json-file Kernel Version: 3.13.0-53-generic Operating System: Ubuntu 14.04.2 LTS CPUs: 12 Total Memory: 31.32 GiB Name: k8s-is-fun.mtv.corp.google.com ID: ADUV:GCYR:B3VJ:HMPO:LNPQ:KD5S:YKFQ:76VN:IANZ:7TFV:ZBF4:BYJO WARNING: No swap limit support

{% endraw %} {% endhighlight %}

With kubectl:

{% highlight console %} {% raw %}

$ kubectl cluster-info Kubernetes master is running at https://108.59.85.141 KubeDNS is running at https://108.59.85.141/api/v1/proxy/namespaces/kube-system/services/kube-dns KubeUI is running at https://108.59.85.141/api/v1/proxy/namespaces/kube-system/services/kube-ui Grafana is running at https://108.59.85.141/api/v1/proxy/namespaces/kube-system/services/monitoring-grafana Heapster is running at https://108.59.85.141/api/v1/proxy/namespaces/kube-system/services/monitoring-heapster InfluxDB is running at https://108.59.85.141/api/v1/proxy/namespaces/kube-system/services/monitoring-influxdb

{% endraw %} {% endhighlight %}